Telephone-exchange system



, H. W. MACDOUGALL- TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 24, I917.

Patented Aug. 12,1919..

UNITED STATES PATENT 'onnron- HARRY W. MAGDOUG'ALII, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Application filed November 24, 1917. Serial No. 203,737.

To all whom it may concern:

Be it known that I, HARRY W. MAODOU- GALL, a citizen of the United States, residing at East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems in which connections are established between telephone lines terminatin at different switchboards.

In such systems, in establishing connections between local and toll lines, it is usual for the local operator, when receiving a call for a toll line, to connect the calling line with a trunk circuit extending to a recording operator who then finds out from the calling subscriber the number or name of the desired party and fills out a toll ticket giving the proper instructions to the toll operator. This ticket is then forwarded to the toll operator, and the recording operator, upon disconnecting from the recording trunk circuit, causes a signaling device of the local link or connecting circuit to furnish to the originating operator a characteristic signal commonly known as a peremptory disconnect signal. The local or originating operator thereupon disconnects the link circuit from the recording trunk circuit and the calling line. The connection between the calling and the wanted toll lines is now built up under direction of the toll operator upon receipt of the toll ticket. 7

It is an object of this invention to provide improved signaling means for systems of this character.

It is another object provide a system of this character in which the noise in the receiver of the calling party,

due to the operation of the peremptory disconnect signal controlling apparatus, is reduced to a minimum.

For a more complete understanding of this invention, reference should be had to the following description considered in connection with the accompanying drawing illustrating one embodiment thereof.

In the drawing there is shown a record ing trunk circuit A extending from a local of this invention to,

or originating operators position X of a switchboard to a recording operators desk Patented Aug. 12, 1919. 1

or switchboard Y. At the local board X there is a cord circuit B which may be employed in connecting a calling subscribers line D with the recording trunk circuit A. At the recording operators desk Y, there is a cord circuit C, by means of which the re-- cording operator may answer calls over and connect the telephone set with the recording trunk circuit.

Assuming that the operator at the local board X receives a call for a toll line, plug 5 of the cord circuit B is immediately inserted into jack 6 of the recording trunk circuit A, whereupon the calling supervisory lamp 7 is lighted and relay 8 operated. The operation of relay 8 causes the actuation of a ringing relay 9 over a circuit from battery through resistance 10, winding of relay 9, normal contact of relay 11, contact of tripping relay l2 and the closed contact of relay 8 to ground. The operation of the ringing relay 16 being of low impedance. Relay 12,-

in operating, opens its contact, removing a short circuit from and permitting relay 11 to operate. Relay 11 is thereupon locked up over a circuit from battery through resistance 10, alternate contact and winding of relay 11 and the contact of relay 8 to ground.

The operation of relay 11 also establishes a short circuit for the ringing relay i), which thereupon releases, removmg ringlng current from the trunk circuit.

Relay 16, in operating, opens a short circuit about the winding of relay 17, which thereupon operates-overa circuit from battery through the lamp 7, winding of relay 8, sleeve contacts of the plug 5 and the jack 6 and the winding of relay 17 to ground. The operation of relay 17 closes a normally open contact of the ring strand of the recording trunk circuit and disconnects relay 16 from across the talking strands thereof. Relay 17, in operating, also causes the operation of relay 18 over a circuit from battery through winding of relay 18, contact 19 of relay 20 and the lower alternate contact of relay 17 to ground. Relay 18,51 operating, causes a lamp 21 to be lighted over a circuit from battery through contact 22 of relay 18, con tact 23 of relay 20 and the lamp 21 to ground.

The recording operator, observing the lighted condition of the lamp 21, inserts plug 25 of cord circuit G into jack 26 of the recording trunk circuit A, whereupon relay 31 is operated. The operation of relay 31 causes the energization of relay 20 which is then locked up through its contact 32 and the lower alternate contact of relay 17. The closure of the upper contact of relay 31 causes the energization of relays 30 and 33 over a circuit from battery through the winding of relay 30, lower normal contact of ringing relay 9, ring contacts of the plug 5 and the jack 6, upper alternate contact of relay 17, upper contact of relay 31, Wind ing of relay '33, tip contacts of the jack 6 and the plug 5, and the upper normal contact of ringing relay 9; to ground. The

operation of relay 33 completes the talking circuit through to the recording operators' cord circuit C, after having disconnected battery and'the impedance coil 34 from the terminating end of the trunk circuit. The operation of the calling supervisory relay 30 connects resistance 10 in shunt of the calling supervisory lamp 7, which is thereextinguished.

The toll operator may actuate listening key 35 to connect the telephone set with the trunk circuit and may thereupon converse with the calling subscriber to obtain the desired information. After the desired information is obtained the toll operator may restorethe listening key 35 to normal positionand withdraw the plug 25 from the jack 26. Relay 31 is thereupon released, which, in turn, releases relay 18. The release of relay 31-causes the release of a calling supervisory relay 30 and the relay Therefore, the denergization of the relay 18 establishes an energizing or operating circuit for the supervisory relay 30, which may betraced from battery through the winding of relay 30, lower normal contact of ringing relay 9, ring contacts of the plug 5 and the jack 6, upper alternate contact of relay 17 contact 40 of relay 18, contact 41 of relay 20 and resistance coil 42 to ground. The denergization of relay 18 also establishes a circuit for relay 43 which may be traced from battery through interrupter 47,

winding of relay 43, contact 44 of relay 20 and contact 45 of relay 18 to ground. Relay 43 is thereupon intermittently energized and intermittently establishes a shunt circuit including the resistance 46 about the winding of the supervisory relay 30 which causes the intermittent deenergization of this relay 30. The intermittent denergization of calling supervisory relay 30 causes the intermittent lighting of. the supervisory ner previously described.

lamp 7 to furnish to the originating operator a peremptory disconnect signal. The operator, upon observing the intermittent operation of this lamp 7 immediately with draws the plug 5 from the jack 6, whereupon the apparatus is restored to normal condition.

If, while the plug 5 is inserted into the jack 6 and the plug 25 is inserted into the jack 26, the originating operator wishes to attract the attention of the toll operator, this may be done by the repeated with drawal of the plug 5 from the jack 6 and the reinsertion therein. The withdrawal of the plug 5 causes all apparatus of the cord circuit B to be restored to normal condition and also causes the release of relays 17 and 33. While the plug is withdrawn from the jack and relay 33 is released, battery is connected to the cord circuit C and the winding of the supervisory relay 50 through the windings of impedance coil 34. Supervisory relay .50 is thereupon energized to light the supervisory lamp 51. The reinsertion of the plug 5 into jack 6 causes the operation of relays 8, 9, 12, 16, 17 and 11, then the release of relay 9 followed by the energization of relays 30 and 33 in the man- The energization of relay 33 disconnects battery from the winding of supervisory relay 50, whereupon the lamp 51 is extinguished. The repeated withdrawal of the plug 5 and the reinsertion thereof will, therefore, cause the intermittent lighting of the supervisory lamp 51, which is a signal for the toll operator that the originating operator is calling. After this repeated withdrawal and reinsertion of the plug 5 the originating operator may ac tuate the listening key 36 to connect the telephone set in circuit so that the two operators may converse when the toll operator has actuated listening key 35.

lVhat is claimed is:

1. In a. telephone exchange system, the comlbination of a trunk circuit extending from a. first to a second switchboard, a link circuit at each switchboard connected with the trunk circuit, a signaling device at the first switchboard associated with the link circuit thereat, a relay at the first switchboard for controlling the signaling device, means responsive to the disconnection of the link circuit at the second switchboard from the trunk circuit, an operating circuit for the relay completed upon the response of said means, and means responsive to such disconnection for intermittently closing a shunt circuit for the relay, thereby causing the intermittent operation of the signaling device.

2. In a telephone exchange system, the combination of' a trunk circuit extending from a first to a second switchboard, a link circuit at each switchboard connected with the trunk circuit, a signaling device at the first switchboard associated with the link circuit thereat, a relay at the first switchboard for controlling the signaling device, an operating circuit for the relay, means responsive to the disconnection of the link circuit at the second switchboard from the trunk circuit for completing the operating circuit, and a relay responsive to such disconnection for intermittently closing a shunt circuit for the first relay, thereby causing the intermittent operation of the signaling device.

3. In a telephone exchange system, the combination of a trunk circuit extending from a first to a second switchboard, a link circuit at each switchboard connected with the trunk circuit, a signaling device at the first switchboard associated with the link circuit thereat, a relay at. the first switchboard for controlling the signaling device, a second relay responsive to the disconnection of the link circuit at the second switchboard from the trunk circuit, an operating circuit for the first relay completed upon the response of the second relay, and a shunt circuit for the first relay there-after inter mittently completed for causing the intermittent operation thereof and of the sig naling device.

4. In a telephone exchange system, the combination of a trunk circuit extending from a first to a second switchboard, a link circuit at each switchboard connected with the trunk circuit, a ignaling device at the first switchboard associated with the link circuit thereat, a relay at the first switchboard for controlling the signaling device, a second relay responsive to the disconnection of the link circuit at the second switchboard from the trunk circuit, an energizing circuit for the first relay completed upon the response of the second relay, a shunt circuit for the first relay for causing the deenergization thereof, a third relay controlling the shunt circuit, and an interrupter connected in circuit with the third relay upon the response of the second relay, therebyto cause the intermittent operation of the signaling device.

5. In a telephone exchange system, the combination of a trunk circuit extendin from a first to a second switchboard, a lin circuit at each switchboard connected with the trunk circuit, a signaling device at the first switchboard associated with the link circuit thereat, a relay at the first switchboard for controlling the signaling device, means responsive to the disconnection of the link circuit at the second switchboard from the trunk circuit, an energizing circuit for the relay established upon the response of said means, a normally ineffective disabling path for the relay, and means operative upon such disconnection for rendering the disabling path intermittently efiective, thereby to cause the intermittent operation of the signaling device.

6. In a telephone exchange system, the combination of a trunk circuit extending from a first to a second switchboard, a link circuit at each switchboard connected with the trunk circuit, a signaling device at the first switchboard associated with the link circuit thereat, a relay at the first switchboard for controlling the signaling device, a second relay deenergized upon the disconnection of the link circuit at the second switch board from the trunk circuit, an energizing circuit for the first relay established upon the deenergization of the second relay, a. normally ineffective disabling path for the first relay, a third relay, and an interrupter connected in circuit with the third relay upon the deenergization of the second relay for rendering the disabling path intermittently effective, thereby to cause the intermittent operation of the signaling device.

In witness whereof, I hereunto subscribe my 7name this 17th day of November, A. D., 191

HARRY w. MAoDOUGALL.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. O. 

